Experimental investigations on P22/P91 dissimilar shielded metal arc welds for power plant applications

This article deals with the development of shielded metal arc welding electrodes for P22/P91 welds. A comparison has also been drawn with commercially available electrodes. P22 low alloy steel matching electrodes developed in the laboratory using a mixture design approach was employed to fabricate the dissimilar weld. Experimentations were performed to evaluate the microstructure and mechanical properties of microhardness, tensile strength, and impact energy of the welds. The impact strength was found to improve by 19% for a laboratory developed electrode made welds as compared to the commercial electrodes. The weld chemistry investigations indicate that the weld fabricated with laboratory-developed electrodes have a higher amount of chromium and molybdenum. These elements are known to enhance the corrosion resistance of joint, thereby imparting enhanced structural integrity in high temperature operating conditions. The electrodes designed and developed in this work are found to enhance the properties of P22/P91 joint much better as compared to that with the commercial electrodes.